The basic theory and operation of thermoelectric devices has been developed for many years. Modern thermoelectric devices typically include an array of thermocouples which operate by using the Peltier effect. Thermoelectric devices are essentially small heat pumps which follow the laws of thermodynamics in the same manner as mechanical heat pumps, refrigerators, or any other apparatus used to transfer heat energy. The principal difference is that thermoelectric devices function with solid state electrical components (thermocouples) as compared to more traditional mechanical/fluid heating and cooling components.
When DC electrical power is applied to a thermoelectric device having an array of thermocouples, heat is absorbed on the cold side of the thermocouples and passes through the thermocouples and is dissipated on the hot side of the thermocouples. A heat sink (sometimes referred to as the "hot sink") is preferably attached to the hot side of the thermoelectric device to aid in dissipating heat from the thermocouples to the adjacent environment. In a similar manner a heat sink (sometimes referred to as a "cold sink") is often attached to the cold side of the thermoelectric device to aid in removing heat from the adjacent environment. Thermoelectric devices are sometimes referred to as thermoelectric coolers. However, since they are a type of heat pump, thermoelectric devices can function as either a cooler or a heater.
There are a wide variety of containers and enclosed structures which are designed to be maintained within a selected temperature range. Examples of such containers and enclosed structures include, but are not limited to, "ice chests", picnic coolers, cabinets containing sensitive electronic equipment, and organ transplant containers. The use of thermoelectric devices which operate on a 12-volt DC system are well known to maintain desired operating temperatures in portable refrigerators or cooler associated with various types of motor vehicles. An example of a container having a thermoelectric cooler is shown in U.S. Pat. No. 4,726,193 entitled "Temperature Controlled Picnic Box". This patent is incorporated by reference for all purposes within this application.